Was Robert E. Lee guilty of treason? I have written The Secret Trial of Robert E. Lee to explore that question. But I am already getting letters from readers who are shocked by my temerity. Once more I find myself in an argument about the role of the novel in examining historical truth.

A great many people tend to think of fiction and nonfiction as opposites; one deals with make-believe, the other with facts. I totally disagree with this wrong division, which unfortunately permeates an amazing number of minds. Too often, I have been told by intelligent readers (most of them men): "I don't read fiction." They are often nonplused to discover that I am also the author of quite a few nonfiction books that they have read and liked. They apparently thought that because the two genres were fixed opposites in their minds, one writer could not do both.

Throughout my career, I have always argued that these two kinds of writing can and should be partners in the investigation of the past. The historical novelist does not simply make things up. He or she is not entitled to write anything that comes into his or her head, especially about characters who are part of the historical record. The key idea of successful historical fiction was first articulated by that 19th Century master of the art, George Eliot. She maintained that the historical novelist must rely on the "veracious imagination" to tell the story.

In the 20th Century, the Cornell critic, Cushing Strout, elaborated this idea with gusto. Strout was not content to warn the historical novelist to respect the truth, to do hard research to discover the fundamental facts about his subject, whether it be a political campaign of an upheaval like the New York Draft Riots of 1863. Strout pointed out, with numerous examples, what happened if the novelist was indifferent to the truth or worse, motivated by some febrile political or personal bias. The result was likely to be a story consumed by a "voracious imagination" that soon robbed the book of its vitality and significance.

All well and good, you may say. But in The Secret Trial of Robert E. Lee, you are dramatizing an event that never happened. It is counterfactual history with a vengeance. Not so, I respond. It is no more counterfactual than most historical novels. Almost all of them deal in varying degrees with events that never happened. What makes them acceptable to intelligent readers is their plausibility. The good historical novelist knows how to convince readers that the story could have happened.

In my research for The Secret Trial, I discovered that in 1865, there were tens of thousands of Radical Republicans (aka abolitionists) who wanted to hang General Lee. A considerable number favored hanging every Confederate officer who had achieved the rank of major general and above, as well as President Jefferson Davis and the top politicians of the Confederate government.

Confirming this thirst for vengeance, Lee was in fact indicted for treason by a federal grand jury in Norfolk, Virginia, in June of 1865. He was rescued by a resounding public statement from General Ulysses S. Grant, declaring the indictment violated the terms of the surrender at Appomattox. For readers of The Secret Trial, this statement will have hitherto unexplored depths.

In his book, The Veracious Imagination, Cushing Strout argues that the imagination is not simply a mental device that makes things up. On the contrary, it is an intellectual tool, closely wedded to the writer's intelligence. What it chooses to imagine for a novel is integrally connected to what the writer, consciously or unconsciously, wants to say about the subject. Some critics, convinced of the importance of this point, have called for a ban on the somewhat tawdry term, the historical novel. They argue (and so do I) for "novels of the historical imagination."

Both historians and historical novelists construct narratives. That crucial word comes from narrare, whose latin stem means "knowing." Both groups of writers are in the business of helping readers understand the past with fresh insights and information. But the historical novelist is in search of emotional truth. As more than one critic has pointed out, historians seldom deal with feelings. The historical novelist makes feelings crucial to his narrative.

With this in mind, the historical novelist often focuses on characters who played only minor roles in the factual drama being explored -- in this case the Civil War -- but who were in a unique position to see the emotional dimensions of the narrative. In The Secret Trial, my first choice for this revelatory role was Senator Reverdy Johnson of Maryland. Few people, except the most dedicated Civil War buffs, have even heard of him. But Johnson was a larger than life figure in his day, the successor to Daniel Webster as a giant of the American bar. He was a southerner who deplored slavery and denounced secession -- but had an even lower opinion of southern-hating Radical Republicans. His decision to become General Lee's defense attorney leads to the exploration of more than a few neglected emotional truths.

For Johnson's chief opponent, I chose another little studied figure, Charles A. Dana, Assistant Secretary of War and former managing editor of the New York Tribune. Tall, suave, handsome, with blue eyes aglow with idealism, Dana is different from most radical Republicans. He does not spew insulting names and reckless accusations at Southerners. He seems an eminently reasonable man. But he is a very plausible architect of the secret trial and the equally plausible behind-the-scenes manipulator who intimidated Ulysses S. Grant into going along with it.

Throughout the war Dana's goal has been not merely a military victory over the South -- but a psychological conquest that would break their defiant spirit. It is Robert E. Lee, the man whose personality cast an aura of nobility over the South's resistance -- Lee dangling from a federal gibbet like a common criminal, who will shatter the South's pretensions forever.

But Dana is not the personification of righteousness he seems at first. When he was the managing editor of the Tribune, the southern states, having seceded after Lincoln's election, began forming an army. Dana seized control of the paper from the erratic editor, Horace Greeley, who was appalled by the prospect of Americans spilling each other's blood.

While Greeley (and many others) were in Washington desperately trying to work out a compromise that would avoid bloodshed, Dana began running on the Tribune's front page: "MR. PRESIDENT, WHEN SHALL THE BAYONETS FLASH TO THE 'FORWARD'? ON TO RICHMOND IS THE VOICE OF THE PEOPLE! AGAIN, WE REPEAT, ON TO RICHMOND!"

Well over 100 other Republican newspapers took up the cry. Soon the harried president overruled his generals, who warned him that his 75,000 untrained volunteers were woefully unready for battle, and ordered an advance on Richmond. The result was the bloody clash at Bull Run and the all out war that killed 625,000 young Americans.

Was it possible, Senator Reverdy Johnson asks the judges, that Charles A. Dana, not Robert E. Lee, should be the man on trial for his life? Here is the ultimate reason why I like to write novels of the historical imagination. You can play for the highest emotional stakes.